Quick demountable load tap changer terminal

ABSTRACT

A quick demountable clamp-type electrical connector of cylindrical shape for use in a high voltage environment where space is limited such as that which occurs at the connection between a load tap changer and its associated power transformer. The connector has an opening at one end, offset from the longitudinal centerline of said connector, which mates with a male terminal. This offset opening permits the use of a clamping arrangement that results in a quick demountable compact unitary connector with a relatively smooth projection free exterior surface which produces relatively low voltage stresses in a high voltage environment.

United States Patent [191 Ettinger [4 Nov. 5, 1974 QUICK DEMOUNTABLE LOAD TAP CHANGER TERMINAL [75] Inventor: Robert H. Ettinger, Pittsfield, Mass. [73] Assignee: General Electric Company [22] Filed: Aug. 2, 1973 [21] Appl. N0.: 385,080

[52] U.S. Cl. 339/263 R, 403/290, 339/272 R .[51] Int. Cl H01r 7/08 [58] Field of Search 339/263, 264, 265, 266,

[56] References Cited UNITED STATES PATENTS 2,216,344 10/1940 Hampton 339/266 R 3,407,382 10/1968 Haegert 339/263 B 3,612,582 10/1971 Pitner 403/290 OTHER PUBLICATIONS Gen. Electric Review, 9-1950, Conduit Fittings Primary Examiner-Roy D. Frazier Assistant Examiner-Robert A. Hafer Attorney, Agent, or Firm-John J. Kelleher; Francis X. Doyle; Volker R. Ulbrich [57] ABSTRACT A quick demountable clamp-type electrical connector of cylindrical shape for use in a high voltage environment where space is limited such as that which occurs at the connection between a load tap changer and its associated power transformer. The connector has an opening at one end, offset from the longitudinal centerline of said connector, which mates with a male terminal. This offset opening permits the use of a clamping arrangement that results in a quick demountable compact unitary connector with a relatively smooth projection free exterior surface which produces rela-' tively low voltage stresses in a high voltage environment.

5 Claims, 4 Drawing Figures QUICK DEMOUNTABLE LOAD TAP CHANGER TERMINAL BACKGROUND OF THE INVENTION This invention relates to connectors in general, and more particularly to such connectors as are used on high voltage electrical connectors of the type used in power transformer load tap changers where space is limited. The invention, however, is not limited to such connectors, as in its broadest aspects it is capable of general application, it being applicable wherever a connection must be made in high voltage conductors and space in the vicinity of the connection is limited.

Load tap changers are devices that select the appro- I priate power transformer output voltage for the load being supplied by such a transformer. A power transformer is one that usually steps up voltage to a magnitude in excess of several hundred kilovolts. These load SUMMARY OF THE INVENTION A quick demountable connector has been devised for use in a high voltage environment where space is limited, such as that which occurs at the connection between a load tap changer and its associated power transformer. The connector is made of an electrically conductive material, such as metal, and is in the shape electrical terminals. In a high voltage environment it is desirable to provide a connector having'a smooth exterior surface free of outward projections and sharp corners thereby avoiding the voltage stresses, dielectric breakdown and arc-over resulting from such shapes. In order to reduce voltage stresses caused by using connectors with such irregularlyshaped external surfaces in a high voltage environment, the timeconsuming procedure of contouring these irregular shapes with a putty filler and then wrapping the contoured region with both aluminum backed and oil impregnated paper insulating tapes was employed.

Prior to shipping a load tap changer with its associated transformer, the load tap changer and transformer are assembled as a unit for testing purposes, including contouring and wrapping the external surfaces of these irregularly shaped prior art connectors. Upon completion of testing, the filler and various tapes are removed from the connector in order to expose the connector attaching means so that the load tap changer can be disconnected from its associated power transformer.

In order to avoid these and other disadvantages it would be desirable'to provide a connector for connecting a load tap changer to its associated transformer which is quick demountable, which has a smooth exterior surface and which is relatively compact in size.

Accordingly, a' primary object of the present invention is to provide a new and improved quick demountable terminal for connecting a load tap changer to its associated transformer.

Another object of the present invention is to provide a new and improved connector for use in a high voltage environment which has a smooth exterior surface.

A further object of the present invention is to provide a new and improved connector for use in a high voltage environment that is relatively compact in size.

of an elongated cylinder. One end of the cylinder is formed into a standard crimp-type fitting and the other connector end has an opening whose longitudinal axis is oriented generally parallel to and displaced a substantial distance or is offset from the longitudinal axis of the elongated cylindrical connector. This opening creates a wall between said opening and the outer surface of the cylindrical connector. Opening offset causes wall thickness to vary from a minimum thickness at one radius on the cylindrical connector to a maximum thickness diametrically opposite the minimum thickness radius. A longitudinally extending slot connecting the opening to the exterior of the connector is cut in the maximum wall thickness portion of the connector. The length of the longitudinally extending slot is at least as long as the depth of the opening. Clamping means are attached to and are connected between those portions of the connector adjacent the longitudinally extending slot. Force exerted by the clamping means bends the connector in the region of minimum connector wall thickness, which reduces slot thickness and opening dimensions, thereby clamping the subject connector to a mating male terminal of appropriate size that has been inserted into said opening to the proper depth. This arrangement results in a quick demountable compact unitary connector with a relatively smooth, projection free exterior surface which produces relatively low voltage stresses in a high voltage reference to the following detailed description of the preferred embodiment thereof, particularly when considered in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view showing the offset opening and longitudinally extending slot of a preferred form of the present invention.

FIG. 2 is a side elevation, partially in section, showing the connector of FIG. I with its offset opening and a pair of screws used in clamping said connector to a male terminal of appropriate size.

FIG. 3 is a view of the end of the connector of FIG. 1 that mates with the appropriate size male terminal.

FIG. 4is a section taken along the line 44 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing wherein like numerals are used to indicate like parts throughout, in FIG. 1 a preferred embodiment of the inventon is shown as an elongated cylindrical connector 12, with an opening 14 at one end whose longitudinal axis 16 (FIG. 3) is displaced a substantial distance from the centerline 18 (FIG. 3) of the cylindrical connector 12. The displacing or offsetting of the opening 14 creates a wall 22 between said opening 14 and the outer cylindrical surface 20 of the connector 12. The offsetting of opening 14 causes the thickness of wall 22 to vary from a minimum wall thickness at 24 to a maximum wall thickness at a position diametrically opposite the minimum wall thickness position 24. A longitudinally extending slot 26 between the opening 14 and the exterior of connector 12 is cut in the maximum wall thickness region of connector 12. Slot 26 divides wall 22 into two portions 28 and 30, said portions being on opposite sides of and immediately adjacent slot 26. Clearance holes 32, 32 in portion 28 of connector 12 are of appropriate size to receive clamping screws 34, 34, the heads of which are best shown in FIG. 2. The small diameter end 36 of connector 12, a cross section of which is shown in FIG. 2, is a crimp-type fitting capable of being crimped onto an electrical conductor of appropriate size. Any equivalent projection free attaching arrangement having a smooth exterior surface may be substituted for the crimptype fitting.

FIG. 4 shows clamping screw 34 of appropriate size inserted through portion 28 of connector 12 and rotated into a threaded hole in portion of connector 12, stopping just before a compressive force is exerted between portion 28 and portion 30 of connector 12 and therefore slot 26 is shown in its normal noncompressed position.

To attach connector 12 to a male terminal (not shown) said male terminal is fully inserted into opening .14 in connector 12. Referring again to FIG. 4, clamping screw 34' is rotated or screwed further into portion 30 of connector 12 than previously described which forces portion 28 toward portion 30. This clamping force causes connector 12 to bend at minimum wall thickness 24, which reduces the size of slot opening 26 and the dimensions of opening 14, thereby clamping connector 12 to a mating male terminal. This procedure is repeated for the other clamping screw 34.

It will be apparent to those skilled in the art, from the foregoing description of the invention, that various improvements and modifications can be made in it without departing from the true scope of the invention. Accordingly, it is my intention to encompass within the scope of the appended claims the true limits and spirit of my invention.

GENERAL CONSIDERATIONS Opening 14 has been described as substantially offset from the longitudinal centerline of connector 12. The word substantial is used because in normal machining operations even an allegedly concentric opening is offset to some degree even though the offset might be barely detectable.

' The amount of offset designed into a connector is a function of the particular connector application. Once minimum physical size of;the connector has been established from power, space limitation, etc. considerations, the amount of offset is then determined. The greater the offset the thinner and therefore weaker is minimum wall portion 24. This permits the use of a smalleramount of clamping force, but if wall'portion 24 is too thin structural failures might result. On the other hand, the smaller the degree of offset the greater is the clamping force required to bend said minimum wall portion 24. The greater force requirement necessitates the use of larger clamping screws which in turn requires that connector diameter increase so that these larger screws can be contained within the cylindrical connector envelope. In actual practice however, the amount of offset is optimized after the previous considerations have been taken into account. The amount of offset, as a practical matter, usually falls somewhere in the neighborhood of half way between the longitudinal centerline of the connector and the outer cylindrical surface of the connector.

The length and diameter of both the male terminal and opening 14 in connector 12 is determined by the amount of surface contact required between the connector and terminal to handle the current being carried by their associated conductors.

To minimize voltage stresses that mght result from' What I claim as new and desire to secure by Letters Patent of the United States is:

1. A clamp-type electrical connector for connecting a cable to a male electrical terminal comprising:

a. an elongated metal cylinder having a longitudinal axis, and having a cylindrical end adapted to receive a cable;

b. said cylinder having a cylindrical opening at an end opposite from the cable end, said opening having a longitudinal axis that is generally parallel to and displaced a substantial distance from the longitudinal axis of said cylinder, said axis of said cable end being parallel to said axis of said cylindrical openmg;

c. a longitudinally extending slot between said opening and the exterior of said cylinder dividing a region of said connector into two portions; and

d. clamping means attached to and connected between said two portions of said cylinder for the purpose of bringing said two portions closer together thereby reducing the dimensions of said opening, and clamping said electrical connector to a mating male electrical terminal.

2. A clamp-type electrical connector as defined in claim 1 wherein the clamping means are contained wholly within the outer surface of said clamp-type electrical connector.

3. A clamp-type electrical connector as defined in claim 1 wherein the end adapted to receive a cable is of the type that can be crimped onto said cable.

4. A clamp-type electrical connector as defined in claim I wherein said clamping means comprises at least one bolt, having a threaded end and a head end, the threaded end of said bolt being screwed into one portion of said connector to the point where the head of said bolt engaged the remaining portion of said connector and forces both portions together to the desired clamped position.

5. A clamp-type electrical connector as defined in claim 4 wherein said clamping means comprises a multiplicity of bolts. i 

1. A clamp-type electrical connector for connecting a cable to a male electrical terminal comprising: a. an elongated metal cylinder having a longitudinal axis, and having a cylindrical end adapted to receive a cable; b. said cylinder having a cylindrical opening at an end opposite from the cable end, said opening having a longitudinal axis that is generally parallel to and displaced a substantial distance from the longitudinal axis of said cylinder, said axis of said cable end being parallel to said axis of said cylindrical opening; c. a longitudinally extending slot between said opening and the exterior of said cylinder dividing a region of said connector into two portions; and d. clamping means attached to and connected between said two portions of said cylinder for the purpose of bringing said two portions closer together thereby reducing the dimensions of said opening, and clamping said electrical connector to a mating male electrical terminal.
 2. A clamp-type electrical connector as defined in claim 1 wherein the clamping means are contained wholly within the outer surface of said clamp-type electrical connector.
 3. A clamp-type electrical connector as defined in claim 1 wherein the end adapted to receive a cable is of the type that can be crimped onto said cable.
 4. A clamp-type electrical connector as defined in claim 1 wherein said clamping means comprises at least one bolt, having a threaded end and a head end, the threaded end of said bolt being screwed into one portion of said connector to the point where the head of said bolt engaged the remaining portion of said connector and forces both portions together to the desired clamped position.
 5. A clamp-type electrical connector as defined in claim 4 wherein said clamping means comprises a multiplicity of bolts. 